.TH std::overflow_error 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::overflow_error \- std::overflow_error

.SH Synopsis
   Defined in header <stdexcept>
   class overflow_error;

   Defines a type of object to be thrown as exception. It can be used to report
   arithmetic overflow errors (that is, situations where a result of a computation is
   too large for the destination type).

   The only standard library component that throws this exception is      \fI(until C++11)\fP
   std::bitset::to_ulong.
   The only standard library components that throw this exception are     \fI(since C++11)\fP
   std::bitset::to_ulong and std::bitset::to_ullong.

   The mathematical functions of the standard library components do not throw this
   exception (mathematical functions report overflow errors as specified in
   math_errhandling). Third-party libraries, however, use this. For example, boost.math
   throws std::overflow_error if boost::math::policies::throw_on_error is enabled (the
   default setting).

   std-overflow error-inheritance.svg

                                   Inheritance diagram

.SH Member functions

   constructor   constructs a new overflow_error object with the given message
                 \fI(public member function)\fP
   operator=     replaces the overflow_error object
                 \fI(public member function)\fP

std::overflow_error::overflow_error

   overflow_error( const std::string& what_arg ); \fB(1)\fP
   overflow_error( const char* what_arg );        \fB(2)\fP
   overflow_error( const overflow_error& other ); \fB(3)\fP (noexcept since C++11)

   1) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg.c_str()) == 0.
   2) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg) == 0.
   3) Copy constructor. If *this and other both have dynamic type std::overflow_error
   then std::strcmp(what(), other.what()) == 0. No exception can be thrown from the
   copy constructor.

.SH Parameters

   what_arg - explanatory string
   other    - another exception object to copy

.SH Exceptions

   1,2) May throw std::bad_alloc.

.SH Notes

   Because copying std::overflow_error is not permitted to throw exceptions, this
   message is typically stored internally as a separately-allocated reference-counted
   string. This is also why there is no constructor taking std::string&&: it would have
   to copy the content anyway.

   Before the resolution of LWG issue 254, the non-copy constructor can only accept
   std::string. It makes dynamic allocation mandatory in order to construct a
   std::string object.

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy constructor. It can be implicitly defined as long as the
   explanatory strings obtained by what() are the same for the original object and the
   copied object.

std::overflow_error::operator=

   overflow_error& operator=( const overflow_error& other );  (noexcept since C++11)

   Assigns the contents with those of other. If *this and other both have dynamic type
   std::overflow_error then std::strcmp(what(), other.what()) == 0 after assignment. No
   exception can be thrown from the copy assignment operator.

.SH Parameters

   other - another exception object to assign with

.SH Return value

   *this

.SH Notes

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy assignment operator. It can be implicitly defined as long
   as the explanatory strings obtained by what() are the same for the original object
   and the copied object.

Inherited from std::runtime_error

Inherited from std::exception

.SH Member functions

   destructor   destroys the exception object
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP
   what         returns an explanatory string
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP

.SH Example


// Run this code

 #include <iostream>
 #include <limits>
 #include <stdexcept>
 #include <utility>

 template<typename T, int N>
     requires (N > 0) /*...*/
 class Stack
 {
     int top_{-1};
     T data_[N];

 public:
     [[nodiscard]] bool empty() const { return top_ == -1; }

     void push(T x)
     {
         if (top_ == N - 1)
             throw std::overflow_error("Stack overflow!");
         data_[++top_] = std::move(x);
     }

     void pop()
     {
         if (empty())
             throw std::underflow_error("Stack underflow!");
         --top_;
     }

     T const& top() const
     {
         if (empty())
             throw std::overflow_error("Stack is empty!");
         return data_[top_];
     }
 };

 int main()
 {
     Stack<int, 4> st;

     try
     {
         [[maybe_unused]] auto x = st.top();
     }
     catch (std::overflow_error const& ex)
     {
         std::cout << "1) Exception: " << ex.what() << '\\n';
     }

     st.push(1337);
     while (!st.empty())
         st.pop();

     try
     {
         st.pop();
     }
     catch (std::underflow_error const& ex)
     {
         std::cout << "2) Exception: " << ex.what() << '\\n';
     }

     try
     {
         for (int i{}; i != 13; ++i)
             st.push(i);
     }
     catch (std::overflow_error const& ex)
     {
         std::cout << "3) Exception: " << ex.what() << '\\n';
     }
 }

.SH Output:

 1) Exception: Stack is empty!
 2) Exception: Stack underflow!
 3) Exception: Stack overflow!

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

     DR    Applied to        Behavior as published               Correct behavior
   LWG 254 C++98      the constructor accepting const      added
                      char* was missing
                      the explanatory strings of           they are the same as that of
   LWG 471 C++98      std::overflow_error's                the
                      copies were implementation-defined   original std::overflow_error
                                                           object
